chore(editorconfig): Add editorconfig file

Add the editorconfig file in order to be more consistant while writing any document in the
repository.

.editorconfig

@@ -0,0 +1,18 @@
+root = true
+
+[*]
+end_of_line = lf
+insert_final_newline = true
+
+[*.py]
+indent_style = space
+indent_size = 4
+charset = utf-8
+trim_trailing_whitespace = true
+
+[*.md]
+trim_trailing_whitespace = false
+
+[{.travis.yml}]
+indent_style = space
+indent_size = 2